I have a couple issues and they seem to be more with Kunena than Joomla.
Once I've logged in as a registered user and try to access an existing topic in Kunena I sometimes get the error:
HTTP Error 500 (Internal Server Error): An unexpected condition was encountered while the server was attempting to fulfill the request.
Sometimes it works better in one browser than another.
I did check with the hosting company (Rackspace Cloud), they ran tests on the database and it's working perfect.
The site is: [url removed, login to view]
Feel free to create an account and test it.
The other issue seems to be only with Internet Explorer 8 but may also be an issue with other versions. In Kunena when the user tries to reply to a topic/post the user cannot get the cursor into the proper field to type.